On the frequency dependence of oxide trap coupling in nanoscale MOSFETs: Understanding based on complete 4-state trap model

The frequency dependence of oxide trap coupling effect in nanoscale MOSFETs under AC switching condition is discussed thoroughly, with experimental and theoretical studies. By using AC STR measurement, a decreased tendency of trap coupling strength with increased frequency is observed. Rather than conventional 2-state trap model, it is found that only the explanation based on complete 4-state trap model is a reasonable interpretation, verified by Monte-Carlo simulation. The impacts of trap coupling frequency characteristics on digital circuits are also evaluated, showing a frequency-dependent underestimation of transient circuit performance if ignoring the above effect.